An optical coupling device generates or receives an optical signal corresponding to a voltage (or current) signal from a transmission chip. The voltage (or current) signal is used for driving light-emission of a light-emitting element, and the optical signal thus generated is subsequently received by a reception chip. The reception chip converts the optical signal into a voltage (or a current) signal. Optical coupling devices are often used as a circuit for driving a semiconductor element, such as an insulated-gate bipolar transistor (IGBT), that is used for electric power operations. In some applications, an insulating signal coupling device using capacitive coupling or magnetic coupling may be used instead of an optical coupling device.
The optical coupling device can be an integrated circuit (IC) including the transmission chip, the light-emitting element, and the reception chip in one package.
The signal coupling devices may be used under various operating and/or environmental conditions, and thus it is desired for circuit characteristics such as a gain not to vary with changes in operating or environmental conditions.